Conventionally, heat-insulating sheets have been used for various applications. For example, a road-heating process in which heat-insulating sheets using spun-bonded non-woven fabric are heated to a predetermined temperature so as to melt snow has been known. In these heat-insulating sheets, by utilizing a high heat radiating rate of non-woven fabric, heat radiation to the ground surface is carried out so that, in comparison with a snow-melting facility formed by a general construction using hot water pipes, a snow-melting process is carried out in a shorter time.
Moreover, chilled shelves, which are used for displaying and storing foodstuffs in a supermarket, etc., use materials, such as polyethylene terephthalate (PET) films and woven fabric, as heat-insulating sheets. Moreover, in air-conditioning facilities, water pipes, etc., pipes are covered with heat-insulating sheets so as to increase the heat-retentive effect.
However, in the case of the heat-insulating sheet made of a single material of non-woven fabric, since it has no heat-retentive effect, it fails to effectively utilize subterranean heat, resulting in an insufficient heat-insulating effect. The same is true to the heat-insulating sheet made of a single material of PET film.
The present invention has been devised so as to solve the above-mentioned problems, and its objective is to provide a laminated sheet that can improve the heat-insulating effect and heat-retentive effect by utilizing far infrared rays.
Moreover, another objective of the present invention is to provide a laminated sheet that can shorten the snow-melting time, etc., greatly by utilizing heat reflection effect in comparison with a sheet made of a single material of non-woven fabric.
The other objective of the present invention is to provide a general-purpose laminated sheet that has a wide range of applications.